Grindinc



May 30, 1933. c. H. CRAGO GRINDING MILL Filed sept. 24. 1951 Patented May 39, 1933 .UNI/TED STATES PATENT :ori-ICE CLAUDE vHAROLD citeseer Asanitari"nriam), `:NEAR l AUSTRALIA Y GRINDING ivrim y Application filed Septemberg2'4, 1931, Serial No. 564,784, and in Australia Januaryg"16',4 1931. 'F

This invention relatesto grinding mills of thebeater type intended primarily for the reductionof cereals-and other small gauge materials. TheV mill consistsfof anas'sembly "l of discs spaced apart on a driving shaft; and

each armed peripherally with beater blades of rectangular shape held-.by bolts orrivets passed through' cheek rings which are laid ontofithe sides yof the discs. v The teeth are fitted in pairs or as twin teeth, one of each pair or one` member-.of eachtwin tooth offset so `as to overhang laterally of vthe disc. The teeth are sheared from bar steel and they are set into rectangular notches slotted in the rim of the disc. The pairs of teeth are spaced apart symmetrically, the clearance between the adjacent pairs being more or less the length of a tooth. One tooth of each pair is disposed centred, and the others are offsided left and right in successive order. The mill contains any desired number of discs7 usually six to twelve discs being fitted according to the size of the mill; the diameter of the discs may also vary according to the size of the mill.

The beater assembly is set up in a casing, the upper interior portion of which is `formed of or is lined with luted plates or shoes.

Preferably these shoes are fitted replaceably in a casing shell. The bottom of the casing` is fitted with screens. Only small clearance is allowed between the beater ends and the shoe plates and .between the bea-ter ends and the screens. The feed is taken in through a tangential vent in the peripheral wall of the casing. rIhe speed of rotation is variable 1n practice a peripheral speed of twelve thousand to fourteen thousand feet per minute is found to give satisfactory results. The milled product passes out through the screens in the bottom of the casing; the material which remains in the casing is churned and submitted to repeated batterings by the beaters and against the inner faces of the shoes until it is reduced in gauge -sutiiciently to allow it to pass through the screens.

Provisions of exhaust means for removing air borne material from the casing isoptional.

15,0 Doubling of the length of service of the beater lassembly is obtainableby it reversible, that is to say, 4.fitting-the beaters so. that they canbeturned end-for-end thus to bring the unworn-bacl; faces of the beaters into theactive position after their front faces arewornm service. ,I

To assist in keeping downitemperatu're in the imill, the driving'pulley may loe4 filled with propeller blade spokes to operate as, air impellers and vents are provided through the casing -endstov admit air blasts produced by these impellers. f fVv .Y In the accompanying drawing z-vv Y Fig 1 iisja transverse vertical section through the mill;- g Fig. 2 a fragmentary-cross' section; y; l

.Figa fragmentary elevational View ili lustrating one' ofthe fair inway valved ports in the endcoversoflthe' mill casing; and` v Fig. 4 isa fragmentary view 'showingthe method of .forming twin 'teethfon a'- double widthlolank. j .The ca'sing'comprises end covers l and 2, an upper Y section longitudinally -lutedas shownLat Sand having a gravity feed pipe'fi entering iti tangentially, .and alower open frame section in two quadrant;parts '5*' and 6. both fitted-.with gauze screens 7 Ainon'itor casingS houses :the lower A'section '5-'6 and supports the'upper sectioni'. 9l are lugs in the) top partof .themonitor 8 with centrei'ng dowel'screw pins 10 tapped through them for supporting the top ends of the quadrant frames vand gvthebottom endsof'jthese `quadrant frames seat onfa bearer F11. 12 is a conveyor screw in Va, troughwayV 13 in thebottom of the monito-r 8, fory removing milled productU which has ,been delivered through the screens 7 14 are access doors. lare air ports in the end coversl and 2`, 1 6 ar e slide damper-s' for regulating the farea of ,these ports, [and l'Zareair -hoodsfwhich'house and v protectthedamp'v rs and direct air'rdraftinwafrd to the dampered ports; i

The :upper ySectio-1113 Imay be constructed.: as

af shell fitted interiorly lwithfdemountable shoe plates. The liner orshoe plates areilutcdas shown inFijg. l. The flutes should be unsymmetrical in cross section,'thedeepest y externally as the discs.

pat of each concavity being at the leaving en The beater assembly consists of a group of steel discs 20 set up concentrically and spaced apart on a shaft 2l with beater blades 22-23 demountably fixed in their peripheries. The invention consists in the particular means by Which the beater blades 22:23 are fixed in the .discs 20-y The discs 20ans spaced apart on the shaftV 21 between thimings and 28 a driving pulley. The air damper 16 is a slotted platel slidably fitted over the air vent l5 inthe air shield 17, and provided with an operating lever 32 moving over a' check quadrant 3.3.

The beater blades 22-23are sheared from steel bars and as shown in Fig. 1 are fixed in pairs in rectangular notches cut at spacings symmetrically apart in the d isc peripheries. One blade 22 of 'each pair is a straight blade and is disposed in plane with the disc and the other blade of the pair is oIset by bendingrit laterally so that its tip over-hangs the interblade space. The blades 23 are offset alternately right hand and left hand. rIhe butt of each blade is holed and check rings 36 are riveted (37) one on each side of each disc, these rings being of the same diameter The blades 22e-23 are demountablyfixed inthe notches in the disc peripheries by bolts or rivets 38 which passthrough' holes in both cheek rings 36 and through the holes in the blade butts. When the beater blades 22e-23 are Worn on the leading edges the bolts or rivets 38 are drawn and the blades reversed and re-xed. Both edgesvo the blades are thus utilized. The. same result is obtainable by reversing the Whole beater assembly end-for-end. The angle of oii'set should be suiiicient to bring the tips of the' offset blades on one disc near to the tips of the offset blades in the adjacent disc'. It is thus ensured that the feed Will not pass" between the discs Without suffering Vflutell Shoes and swirled over the screens,

The screens pass the fine gauze. material Whilst the coarser gauze stnif is subjected to repeated beating and battering until it is reduced suiiciently to pass through the screens. j l Y Y y Fig: 4 shows a twin bladefermed by splitting a double Width beater'blank for portion of its length and oisetting one of the split ends; when this form of construction -is used one bolt 38 suiiices to hold the butt of the pair toothin the notch in the disc.

What I claim as my invention and desire to secure by Letters Patent is :v

l. In a beater mill of the kind herein described, a cylindrical chamber, an assembly ci discs with notches of rectangular shape Vcut toothwise in their peripheries, 'said discs bles 24, 25 being check pins on the outermost thirnbles and 26 a key. 27 are the shaft bearis being spaced apart on a driving shaft Within said chamber and the diameter of said discs being slightly less than the diameter of the chamber, a pair of cheek rings fixed-at epposite sides of each disc near its periphery, and a plurality of short rectangular shaped beatter blades set in said notches in the plane of the disc and iixedby bolts or rivets passed through their butts and through the cheek rings.

2. A beater mill according to claim 'lvhavf ing the beater blades fitted as twins or in pairs, one blade of each tWinior pair oiset; laterally and the offset blades alternatedleft and right respectively. I

In testimony whereof I aiiix my signature,

CLADE HARQLD CRAGO.

reduction by contact of the oilset blades with 

